Three sucesses.
Not so successful: Solar City, Neuralink, TBC, X.
(X exists, but before it was valued-and-bought by one of Musk's other companies, it appeared to have lost about half its value).
Richard Branson he aint.
They put out this video of a patient with ALS regaining the ability to communicate.
Hard to see that not being successful, once it passes the FDA, assuming it's real.
Of course it’s still early days for all these companies and they’re not exactly fiscally solid, but if Tesla had not made all those cars, someone else would have.